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Why do so many people wear glasses the older people get. In school at early ages, only a few people wear glasses but every year in school this increases and by the time people are in college or start working, so many people wear glasses. Sometimes it seems like over half the population does. Why?
— Preceding
unsigned comment added by
90.194.55.177 (
talk •
contribs) 00:38, 29 June 2014 (UTC)
By the way, in a complex human society with division of labor but without glasses, nearsightedness is not actually a disadvantage. Nearsightedness in adolescence would steer a person into a trade or craft involving near vision, such as weaving or woodworking, and a naturally nearsighted person continues to have good near vision after the onset of presbyopia. In a complex human literate society without glasses, nearsightedness may have actually been beneficial, because one could become a scribe, a high-status occupation. So evolution in humans never selected against nearsightedness. Robert McClenon ( talk) 02:15, 29 June 2014 (UTC)
See Human eye#Effects of aging and Presbyopia. Red Act ( talk) 02:21, 29 June 2014 (UTC)
If limiting career options and one's ability to participate in certain recreational activities isn't a "disadvantage", then I don't know what is. It is a categorical error to confuse what is beneficial to a Society with what is beneficial to an individual. You could (obviously) argue that having no education isn't a disadvantage because some jobs (like toilet cleaner) will always be open to the illiterate and uneducated. Saying that something isn't "necessarily" disadvantageous because there are certain situations where it might be useful is less than honest. I'm near-sighted. I don't especially mind it. My glasses cost me $500-$1000, and contacts also cost money which without my disadvantage I could spend on other things. I have to put them on in the morning, not lose them, not break them, and keep them clean. When I swim, I am certainly at a disadvantage. With water sports, the possibility that I'll lose them is a restriction. When I'm traveling, especially away from "civilization" their loss would be a nuisance at best and life-threatening at worst. By the way, the "disadvantage" post is OPINION. I was told that as children's head grow, some eyes deform leading to an inability of the lens to focus - a simple matter of optics. Most people's lenses also harden with age which also limits the ability of the lens to focus. The human lens is a "bag of gel" which changes focus by stretching and relaxing. http://en.wikipedia.org/wiki/Lens_%28anatomy%29 — Preceding unsigned comment added by 173.189.75.163 ( talk) 14:50, 2 July 2014 (UTC)
Considering the original question of does it feel like more people are wearing glasses in this day and age, the answer is yes. The advancements in detecting disorders as well as the societal changes in this day and age play a huge part. Advancements in medical detection [1] have enabled us to help diagnose common diseases such as Presbyopia [2] which is present in many of us and can have very mild affects to our vision later in life. This is most of the cases of people getting glasses when they get older in life as there Presbyopia progresses. The other main reason for the increase in people who wear glasses in today's society is social acceptance and awareness. For instance it was difficult in the 1800's-1900's to convince men to wear glasses simply because it wasn't seen as a masculine thing to do as well as a sign of weakness. People with vision impairments would think that its normal as well because it is the only way they have seen their entire life. When there is an impairment in vision there has been studies [3] that have shown that people can sometimes have heightened senses such as hearing that can be advantageous for them and they sometimes feel that they do not need glasses. DGG8018 ( talk) 01:27, 4 July 2014 (UTC)DGG8018
Move from Portal talk:Astronomy by -- Moxy ( talk) 08:17, 29 June 2014 (UTC) ...user notified
i've got a question concerning the radius of NML Cygni: this article http://arxiv.org/abs/1207.1850 has been quoted as the source of the radius of 1650 R☉. however, i could not find 1650 R☉ in the article. all i could find was the following sentence on page 10: NML Cyg’s stellar size of 16.2 mas from Blöcker et al.(2001) was derived using the Stepan-Boltzmann law, adopting Teff=2500 K and a distance of 1.74 kpc. Rescaling this stellar diameter with our distance of 1.61 kpc gives 15.0 mas. well, mas are milli arc seconds, i suppose.
using http://www.wolframalpha.com/input/?i=1.61+kpc*sin%2815+milliarcseconds%29 i get a diameter of 3.613 billion km. this is far from the 2.29 billion km quoted for NML Cygni. can anyone explain, how the 1650 R☉ were calculated? many thanks -- Agentjoerg ( talk) 08:01, 29 June 2014 (UTC)
I am trying to find a shortcut method to balance redox equations.
(There is one such method for the simple (non-redox) chemical equations. source: http://www.nyu.edu/classes/tuckerman/adv.chem/lectures/lecture_2/node3.html) (I know the original method to balance an equation by oxidation numbers, but just trying to find if there exists an shortcut method for this. This is not my homework. I can balance these equations, but the original method is too long and boring.)
The problem with this type of equation is - we are not always given H2O and H+ on any of the sides. If we were given all of the resultants and the products, we could solve the equation simply by the algebraic method. (see the link above)
I think that the main thing I have to figure out is - how to determine the side, on which H2O or H+ is, at first sight.
e.g. 1) S + HNO3 ---> H2SO4 + NO 2) P4 + NO3- ---> PO4-3 + NO2 3) FeS + H2O2 ---> FeO + SO2
The answers to the above equations is respectively -- 1) S + 2HNO3 ---> H2SO4 + 2NO 2) P4 + 20NO3- 8H+ ---> 4PO4-3 + 20NO2 + 4H2O 3) FeS + 3H2O2 + 5Fe+2 + 2H2O ---> 6FeO + SO2 + 10 H+
Ravishankar Joshi
No, I think that I have not properly explained the question I have. I already know to balance the equation by Jayron32's method. I just want to know if it is possible to determine the number of H+ or H2O (and their side) just by looking at the equation. Please tell me if that is possible. Ravijoshi99 ( talk) 10:43, 2 July 2014 (UTC)
I'm curious to know if organs are able to be supported outside the body on a long term basis? We know that organs require a healthy blood supply and circulation in order to survive. With modern medicine and science could this not be achieved? Perhaps technology could go a step further in the form of a machine that actually simulates the environment of the body.
Building on this, could we then support a fully functioning female reproduction system? Infants could be spawned without the need for a human host. How feasible would all all this be?
And whilst we're at it, I know during brain surgery the brain is actually exposed with the patient conscious. So what would happen in a scenario with a large portion of the skull missing, exposing the brain. Would the said individual be able to function normally for a period of time (beside the distress of having your brain exposed of course) If not, what would be the cause of death?
Okay, back to my second question regarding brain exposure, I mean literally an exposed brain, no tissue or flesh covering it. Is it possible to function normally in this condition? Obviously, aside from the somewhat obvious mental distress. If not, what would be the cause of death?~~
I have a pair of spoons that, well, "spooned" in the dishwasher. One apparently has a flaw in the surface that allowed iron to escape, and the area between the spoons stayed wet and formed a rust ring on both spoons. I tossed out the one with the flaw, but can the other be saved ? So far I tried using steel wool on it, which removed some, but not all, of the rust stain. Obviously I want to avoid damaging the surface. StuRat ( talk) 17:01, 29 June 2014 (UTC)
I dread to think how long they were left like that for a rust ring to form, weeks at a guess. Anyway the sad thing you have learned is that cheap stainless steel isn't stainless. Greglocock ( talk) 22:23, 29 June 2014 (UTC)
I was told that, at least with acetic acid (vinegar), you have to heat the reactants to start the acid-base reaction. I'm not sure of it, but it may also be possible to use electrolysis to reduce the iron back to the free element (the main problem I can think of is that water might be too easily reduced instead); my book mentions the untarnishing of antique silverware this way.-- Jasper Deng (talk) 03:13, 30 June 2014 (UTC)
I use Bar Keepers Friend to clean rust off my stainless steel sink and burnt spots off of cookware. It's a mild abrasive and an acid. I've never tried it on utensils though. Mr. Z-man 19:00, 1 July 2014 (UTC)
This brings up the obvious Q, how do I find stainless steel flatware that won't have flaws in the surface ? Or do I just buy a really expensive brand and hope they are good ?
1) Is there no way to tell before I make the purchase ?
2) Is there a test I could do immediately when I get them home, so I could return them if defective ? (I'm thinking submerge them in bleach so any corrosion will happen far sooner.) StuRat ( talk) 14:58, 30 June 2014 (UTC)
In the diagram here, is "Area of triangle / Area of grey shape" a sensible estimate of the proportion of the colour space of human vision that can be represented by the RGB colour model? 86.179.117.18 ( talk) 20:23, 29 June 2014 (UTC)
Science desk | ||
---|---|---|
< June 28 | << May | June | Jul >> | June 30 > |
Welcome to the Wikipedia Science Reference Desk Archives |
---|
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages. |
Why do so many people wear glasses the older people get. In school at early ages, only a few people wear glasses but every year in school this increases and by the time people are in college or start working, so many people wear glasses. Sometimes it seems like over half the population does. Why?
— Preceding
unsigned comment added by
90.194.55.177 (
talk •
contribs) 00:38, 29 June 2014 (UTC)
By the way, in a complex human society with division of labor but without glasses, nearsightedness is not actually a disadvantage. Nearsightedness in adolescence would steer a person into a trade or craft involving near vision, such as weaving or woodworking, and a naturally nearsighted person continues to have good near vision after the onset of presbyopia. In a complex human literate society without glasses, nearsightedness may have actually been beneficial, because one could become a scribe, a high-status occupation. So evolution in humans never selected against nearsightedness. Robert McClenon ( talk) 02:15, 29 June 2014 (UTC)
See Human eye#Effects of aging and Presbyopia. Red Act ( talk) 02:21, 29 June 2014 (UTC)
If limiting career options and one's ability to participate in certain recreational activities isn't a "disadvantage", then I don't know what is. It is a categorical error to confuse what is beneficial to a Society with what is beneficial to an individual. You could (obviously) argue that having no education isn't a disadvantage because some jobs (like toilet cleaner) will always be open to the illiterate and uneducated. Saying that something isn't "necessarily" disadvantageous because there are certain situations where it might be useful is less than honest. I'm near-sighted. I don't especially mind it. My glasses cost me $500-$1000, and contacts also cost money which without my disadvantage I could spend on other things. I have to put them on in the morning, not lose them, not break them, and keep them clean. When I swim, I am certainly at a disadvantage. With water sports, the possibility that I'll lose them is a restriction. When I'm traveling, especially away from "civilization" their loss would be a nuisance at best and life-threatening at worst. By the way, the "disadvantage" post is OPINION. I was told that as children's head grow, some eyes deform leading to an inability of the lens to focus - a simple matter of optics. Most people's lenses also harden with age which also limits the ability of the lens to focus. The human lens is a "bag of gel" which changes focus by stretching and relaxing. http://en.wikipedia.org/wiki/Lens_%28anatomy%29 — Preceding unsigned comment added by 173.189.75.163 ( talk) 14:50, 2 July 2014 (UTC)
Considering the original question of does it feel like more people are wearing glasses in this day and age, the answer is yes. The advancements in detecting disorders as well as the societal changes in this day and age play a huge part. Advancements in medical detection [1] have enabled us to help diagnose common diseases such as Presbyopia [2] which is present in many of us and can have very mild affects to our vision later in life. This is most of the cases of people getting glasses when they get older in life as there Presbyopia progresses. The other main reason for the increase in people who wear glasses in today's society is social acceptance and awareness. For instance it was difficult in the 1800's-1900's to convince men to wear glasses simply because it wasn't seen as a masculine thing to do as well as a sign of weakness. People with vision impairments would think that its normal as well because it is the only way they have seen their entire life. When there is an impairment in vision there has been studies [3] that have shown that people can sometimes have heightened senses such as hearing that can be advantageous for them and they sometimes feel that they do not need glasses. DGG8018 ( talk) 01:27, 4 July 2014 (UTC)DGG8018
Move from Portal talk:Astronomy by -- Moxy ( talk) 08:17, 29 June 2014 (UTC) ...user notified
i've got a question concerning the radius of NML Cygni: this article http://arxiv.org/abs/1207.1850 has been quoted as the source of the radius of 1650 R☉. however, i could not find 1650 R☉ in the article. all i could find was the following sentence on page 10: NML Cyg’s stellar size of 16.2 mas from Blöcker et al.(2001) was derived using the Stepan-Boltzmann law, adopting Teff=2500 K and a distance of 1.74 kpc. Rescaling this stellar diameter with our distance of 1.61 kpc gives 15.0 mas. well, mas are milli arc seconds, i suppose.
using http://www.wolframalpha.com/input/?i=1.61+kpc*sin%2815+milliarcseconds%29 i get a diameter of 3.613 billion km. this is far from the 2.29 billion km quoted for NML Cygni. can anyone explain, how the 1650 R☉ were calculated? many thanks -- Agentjoerg ( talk) 08:01, 29 June 2014 (UTC)
I am trying to find a shortcut method to balance redox equations.
(There is one such method for the simple (non-redox) chemical equations. source: http://www.nyu.edu/classes/tuckerman/adv.chem/lectures/lecture_2/node3.html) (I know the original method to balance an equation by oxidation numbers, but just trying to find if there exists an shortcut method for this. This is not my homework. I can balance these equations, but the original method is too long and boring.)
The problem with this type of equation is - we are not always given H2O and H+ on any of the sides. If we were given all of the resultants and the products, we could solve the equation simply by the algebraic method. (see the link above)
I think that the main thing I have to figure out is - how to determine the side, on which H2O or H+ is, at first sight.
e.g. 1) S + HNO3 ---> H2SO4 + NO 2) P4 + NO3- ---> PO4-3 + NO2 3) FeS + H2O2 ---> FeO + SO2
The answers to the above equations is respectively -- 1) S + 2HNO3 ---> H2SO4 + 2NO 2) P4 + 20NO3- 8H+ ---> 4PO4-3 + 20NO2 + 4H2O 3) FeS + 3H2O2 + 5Fe+2 + 2H2O ---> 6FeO + SO2 + 10 H+
Ravishankar Joshi
No, I think that I have not properly explained the question I have. I already know to balance the equation by Jayron32's method. I just want to know if it is possible to determine the number of H+ or H2O (and their side) just by looking at the equation. Please tell me if that is possible. Ravijoshi99 ( talk) 10:43, 2 July 2014 (UTC)
I'm curious to know if organs are able to be supported outside the body on a long term basis? We know that organs require a healthy blood supply and circulation in order to survive. With modern medicine and science could this not be achieved? Perhaps technology could go a step further in the form of a machine that actually simulates the environment of the body.
Building on this, could we then support a fully functioning female reproduction system? Infants could be spawned without the need for a human host. How feasible would all all this be?
And whilst we're at it, I know during brain surgery the brain is actually exposed with the patient conscious. So what would happen in a scenario with a large portion of the skull missing, exposing the brain. Would the said individual be able to function normally for a period of time (beside the distress of having your brain exposed of course) If not, what would be the cause of death?
Okay, back to my second question regarding brain exposure, I mean literally an exposed brain, no tissue or flesh covering it. Is it possible to function normally in this condition? Obviously, aside from the somewhat obvious mental distress. If not, what would be the cause of death?~~
I have a pair of spoons that, well, "spooned" in the dishwasher. One apparently has a flaw in the surface that allowed iron to escape, and the area between the spoons stayed wet and formed a rust ring on both spoons. I tossed out the one with the flaw, but can the other be saved ? So far I tried using steel wool on it, which removed some, but not all, of the rust stain. Obviously I want to avoid damaging the surface. StuRat ( talk) 17:01, 29 June 2014 (UTC)
I dread to think how long they were left like that for a rust ring to form, weeks at a guess. Anyway the sad thing you have learned is that cheap stainless steel isn't stainless. Greglocock ( talk) 22:23, 29 June 2014 (UTC)
I was told that, at least with acetic acid (vinegar), you have to heat the reactants to start the acid-base reaction. I'm not sure of it, but it may also be possible to use electrolysis to reduce the iron back to the free element (the main problem I can think of is that water might be too easily reduced instead); my book mentions the untarnishing of antique silverware this way.-- Jasper Deng (talk) 03:13, 30 June 2014 (UTC)
I use Bar Keepers Friend to clean rust off my stainless steel sink and burnt spots off of cookware. It's a mild abrasive and an acid. I've never tried it on utensils though. Mr. Z-man 19:00, 1 July 2014 (UTC)
This brings up the obvious Q, how do I find stainless steel flatware that won't have flaws in the surface ? Or do I just buy a really expensive brand and hope they are good ?
1) Is there no way to tell before I make the purchase ?
2) Is there a test I could do immediately when I get them home, so I could return them if defective ? (I'm thinking submerge them in bleach so any corrosion will happen far sooner.) StuRat ( talk) 14:58, 30 June 2014 (UTC)
In the diagram here, is "Area of triangle / Area of grey shape" a sensible estimate of the proportion of the colour space of human vision that can be represented by the RGB colour model? 86.179.117.18 ( talk) 20:23, 29 June 2014 (UTC)